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420 Plus Installation Manual
6. When span calibration is complete, a dialog
box asks whether you wish to perform linear
calibration. Click
Ye s
to perform linear
calibration for up to five linearization points, or
click
No
to complete calibration (see step 8).
7. On the Linear Calibration display, select the
point (1–5) to calibrate, then click
Calibrate
.
Place test weights on scale then click
OK
.
When prompted, enter the test weight value
then press Enter. Repeat for additional
linearization points, then click
Exit
to return to
the Indicator Calibration display.
8. When calibration is complete, the
New Settings
fields of the Indicator Calibration display are
filled in. Click
Exit
to save the new values and
return to the
Revolution
main menu; to restore
the previous calibration values, click
Restore
Settings
.
4.4
More About Calibration
The following topics provide additional information
about compensating for environmental factors
(Section 4.4.1) and diagnostic information for
determining expected zero and span coefficients.
4.4.1
Adjusting Final Calibration
Calibration may be affected by environmental factors
including wind, vibration, and angular loading. For
example, if the scale is calibrated with 1000 lb, a
s t r a i n t e s t m a y d e t e r m i n e t h a t a t 2 0 0 0 l b t h e
calibration is 3 lb high. In this case, final calibration
can be adjusted by tweaking WVAL to 998.5 lb. This
adjustment provides a linear correction of 1.5 lb per
1000 lb.
To adjust the final calibration, return to the
WVAL
prompt and press to show the test weight value.
Press or to adjust calibration up or down. Press
to save the value, then press to return to the
CALIBR menu.
4.4.2
Zero Deadload A/D Counts
Table 4-1 lists the ideal A/D counts that result from
input signals of 0–3.0 mV with zero deadload. Actual
values will typically be higher than the values shown
in Table 4-1 but the ideal values can be used when
calibrating the indicator with no attached scale.
When Raw A/D Count is displayed, the six
most significant digits appear. Scroll left or
right to see the full value.
Input Signal (mV)
Raw A/D Counts
0.0 mV/V
167,840
0.5 mV/V
335,613
1.0 mV/V
503,377
1.5 mV/V
671,143
2.0 mV/V
838,908
2.5 mV/V
1,100,668
3.0 mV/V
1,174,446
Table 4-1. Ideal A/D Raw Counts
Note
